Work has progressed in two major areas: (1) models for human fertility; and (2) statistical methods for studying genetic effects. In the first area, we developed a new Bayesian fertility model that can distinguish between factors associated with reduced fecundability and factors associated with sterility. We adapted our model to accommodate possible measurement errors in identifying the day of ovulation, in order to correct for bias in estimation of the fertility parameters and to assess the magnitude of error in commonly used markers of ovulation. Nonreporting of intercourse can also produce bias in fertility studies and methods were developed to correct for this problem and estimate its extent. Case-control studies aimed at elucidating genetic contributors to the etiology of diseases are problematic because of the admixture problem: If a particular variant allele is to be studied, there may be subpopulations that simultaneously have elevated prevalence of the variant and increased risk of the defect, for unrelated reasons. Such an admixture can produce biased estimation in a traditional population- based case-control study. The case-parents design avoids this problem by statistically conditioning on the parental genotypes. Using the genetic triad data from such a study, under assumed Mendelian inheritance, one can estimate relative risks for an allelic variant and can differentiate effects that depend on the prenatal effects of the maternal genotype from effects mediated by the (correlated) offsprings inherited genotype. Triads that are incomplete because one or both parents are not available for genotyping can be fully used by applying the Expectation-Maximization algorithm. Further work allows for detection of effects that differ according to the parent of origin of the variant allele, a phenomenon known as ?imprinting. The method works by conditioning on both the parental genetic mating type and the childs genotype, and then applying a logistic model to statistically test for the presence of imprinting and estimate the imprinting parameter. - genetics, markers, gene-by-environment interaction, fertility, measurement error, admixture, transmission-disequilibrium test, haplotype relative risk